Why doesn't my hydrenga have flowers?

Question

The plants have beautiful green leaves but no flowers.

Answer 1

They only flower when they are mostly in the shade...

Answer 2

How long ago did you plant it?

I planted one about 4-5 years ago and this is the first summer it has flowered.

I bought it in the grocery store and ser it out in the garden.

I'm thinking maybe the plants that are shipped to the groceries aren't as developed as the plants you might buy in a nursery/garden center.  Hydrangeas bought at a garden center would probably bloom more reliably sooner.